PROPOSED NATIONAL BANK OF KENYA LTD, MOMBASA POLYTECHNIC UNIVERSITY COLLEGE BRANCH-MOMBASA. FORNATIONAL BANK OF KENYA LTD P.O. BOX 72866-00200 NAIROBI. MECHANICAL ENGINEERING SERVICES SUB – CONTRACT CONDITIONS, SPECIFICATIONS AND BILLS OF QUANTITIES FOR AIR CONDITIONING AND MECHANICAL VENTILATION NAME OF TENDERER: .....................................................................…. ………………………………………………………………………… ELECTRICAL/MECHANICAL ENGINEERS’ ARCHITECTS SYNCHROCONSULT ASSOCI ATES LTD BOUNDLESS ARCHTECTS P. O. BOX 79626 00200 P.O. BOX 9668-00100 NAIROBI NAIROBI QUANTITY SURVEYORS NDERITU CONSULTANTSP.O.BOX 62405-00200 NAIROBI STRUCTUENGINEERS XENOCON CONSLTINGNGI P.O00200
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1. I/We understand that works, the subject of this tender, are covered by a prime cost of
provisional sum in the main contract entered into by the main contractor.
I/We shall become a Nominated sub-Contractor, that is to say, a sub-contractor nominated
by the Architects under the terms and conditions of the current form of agreement and
schedule of conditions, of Building Contract published by the Architects Association of
Kenya (latest edition with quantities).
2. It is confirmed that I/we have notice of all the provisions of the main contract including the
detailed prices of the contract in the schedule and Bill of Quantities.I/We undertake in accordance with the particulars set out in the preliminaries and to the
satisfaction of the Architects, to execute and complete the sub-contract works as described
in the specification and drawings for the sum of KENYA SHILLINGS
3. I/We confirm that this Tender is subject to adjustments by any variation ordered by theArchitects in accordance with the terms of the main contract.
4. I/We undertake to commence the works within 7 days from the date of official confirmation
of the acceptance of the Tender.
5. I/We further undertake to complete the work in accordance with the Main Contractors
programme.
6. I/We agree that this Tender shall be open for acceptance by the Architects within 90 days
from the date given below.
6. I/We understand that you are not bound to accept the lowest or any tender
1. The tenderer shall make sure that he has received all pages of the specification and thedrawings on which this tender is based. Should the tenderer be in doubt on the precise meaning
of any item, word or figures, or observe any apparent omission of words or figures, he must
inform the Engineer in order that the correct meaning may be decided upon before the date for
the submission of the tender.
2. The tenderer shall complete in full such pages where he is required to do so.
3. Any alternative tenders for portions or the whole of the works will be considered as far as the
alternatives are clearly separated from the original tender. All alternative tenders must be
accompanied by a full and comprehensive specification of the alternative materials and design.
4. The tenderer shall be deemed to have made allowance in his prices generally to cover items of
preliminaries or additions to prime cost sums or other items, if those have not been priced
against the respective items.5. The subcontractor shall comply with the main contractor’s working programme.
6. The copyright of this specification is vested with the Engineer and no part thereof may be
reproduced without his express permission given in writing.
7. The subcontractor shall be solely responsible for the accurate ordering of materials in
accordance with the drawings and specification.
8. The specification must be priced in Kenyan currency.
DEFINITIONS
EMPLOYER
The employer is NATIONAL BANK OF KENYA LTD of P.O Box 72866-00200 NAIROBI
ENGINEER
The term ‘the Engineer’ shall in the case of Mechanical and Electrical Engineering works mean;SYNCHROCONSULT ASSOCIATES of P.O BOX 79626 00200 NAIROBI
ARCHITECT
The term ‘The Architect’ shall be deemed to mean;BOUDLESS ARCHITECTS of P.O. BOX 9668-00100 NAIROBI
QUANTITY SURVEYOR
The term ‘Quantity Surveyor’ shall be deemed to mean;
NDERITU CONSULTANTS of P.O BOX 62405 NAIROBI
THE CONTRACTOR
The term ‘contractor’ shall be deemed to mean the firm appointed by the employer to carry out the
Where control panels incorporating several starters are supplied, they shall be complete
with a main isolator.
The supply power upto and including local isolators will be provided and installed by the
Electrical subcontractor. All other wiring shall be as described in part C – the particular
specification.
The subcontractor shall supply three copies of all schematic, cabling and wiring diagrams
for the Engineer’s approval.
The starting current of all electric motors and equipment shall not exceed the maximum
permissible starting currents described in the Kenya power and Lighting Company’s by-
Laws.
All electrical plant and equipment supplied by the subcontractor shall be rated for the
supply voltage and frequency obtained in Kenya i.e. 415 volts, 50 Hz, 3-phase or 240
volts ,50hz , 1- phase as specified in part ‘C’ –the particular specification.
Any equipment that is not rated for the above voltage and frequencies may be rejected by
the Engineer.
2.5 TRANSPORT AND STORAGE
All plant and equipment shall, during transportation be suitably packed, crated to minimize
the possibility the possibility for damage, and to prevent corrosion or other deterioration.
On arrival at the site all plant and equipment shall be examined and any damage to parts
and protective priming coats made good before storage or installation.
Adequate measures shall be taken by the subcontractor to ensure that plant and equipment
do not suffer any deterioration during storage.
Prior to installation all piping, plant and equipment shall be thoroughly cleaned.
If in the opinion of the Engineer any equipment has deteriorated or been damaged to such
an extent that it is not suitable for installation, the subcontractor shall replace this
equipment at his own cost.
2.6 SITE SUPERVISION
The subcontractor shall ensure that there is an English speaking Supervisor on the site at all
times during normal working hours.
2.7 INSTALLATION
Installation of all special plant and equipment shall be carried out by the subcontractor
under adequate supervision from skilled staff provided by the plant and equipment
manufacturer or his appointed agent, in accordance with the best standards of modern
practice and to the relevant regulations and standards described under clause 2.3 of this
section.
2.8 TESTING
2.8.1 GENERAL
All testing shall be carried out to the entire satisfaction of the Engineer.
The following sub-clauses are intended to define the subcontractor’s responsibilities with
respect to testing and inspection.
2.8.2 MATERIAL TESTS
All materials for plant and equipment to be installed under this subcontract shall be tested,unless otherwise directed, in accordance with relevant B.S. specification concerned.
For materials where no B.S. specification exists, tests are to be made in accordance with the
best modern commercial methods to the approval of the Engineer having regard to the
particular type and application of the materials concerned.
The subcontractor shall prepare specimens and performance tests and analyses to
demonstrate conformance of the various materials with the applicable standards.
If stock material, which has not been specifically manufactured for the plant and equipment
specified is used, then the subcontractor shall submit satisfactory evidence to the Engineer
that such materials conform to the requirements stated herein in which case test of the
material may be partially or completely waived.
Certified mill test reports of plates, piping and other materials shall be deemed acceptable.
2.8.3 MANUFACTURED PLANT AND EQUIPMENT- WORK TESTS
The rights of the Engineer relating to the inspection, examination and testing of plant and
equipment during manufacture shall be applicable to the insurance companies or inspection
Authorities so nominated by the Engineer.
The subcontractor shall give two weeks notice to the Engineer of the manufacturer’s
intention to carry out work tests and inspection.
The Engineer or his representative shall be entitled to witness such tests and inspections.The costs of such tests and inspections shall be borne by the subcontractor.
Six copies of all test and inspection certificates and performance graphs shall be submitted
to the Engineer for his approval as soon as possible after the completion of such tests and
inspections.
Plant and equipment which is shipped before the relevant test certificate has been approved
by the Engineer shall be shipped at the contractor’s own risk and should the test and
inspection certificate not be approved, new tests may be ordered by the Engineer at the
subcontractor’s expense.
2.8.4 PRESSURE TESTING
All pipe work installation shall be pressure tested in accordance with the requirements of
the various sections of this specification. The installation may be tested in sections to suit
the progress of the works but all tests must be carried out before the work is buried or
concealed behind building finishes. All tests must be witnessed by the Engineer or his
representative and the subcontractor shall give 48 hours notice to the Engineer of his
intention to carry out such tests.
Any pipe work that is buried or concealed before witnessed pressure tests have been carried
out shall be exposed at the expense of the subcontractor and the specified tests shall then be
carried out.
The subcontractor shall prepare test certificates for signature by the Engineer and shall keepa progressive and up to date certificate of the sections of work that have been tested.
2.9 COLOUR CODING
Unless stated otherwise in the particular specification all pipe work shall be color coded in
accordance with in accordance with the latest edition of
This section specifies the general requirements for mechanical ventilation and air
conditioning plant, equipment and materials forming part of the subcontract works and
shall apply except where specifically stated elsewhere in the specification or on the
contract drawings.
2.0 INSTALLATION
Installation of all ductwork, plant and equipment shall be carried out under adequate
supervision from skilled staff to the relevant Codes and Standards specified herein.
The subcontractor shall be responsible for ensuring that sufficient provisions are made to
prevent the transmission of vibration from the equipment to the supporting structure. In the
case of fans, this shall be done by rot and vermin- proof flexible connections and
antivibration mountings of an approved type.
The subcontractor shall ensure that all ducting systems are provided with sufficient access
hatches complete with covers, for maintenance purposes.
Dampers and other user equipment shall be installed with adequate access for operation and
maintenance. Where dampers and other operational equipment are unavoidably installed
beyond normal reach, and in such a position as to be difficult to reach from a short step
ladder, extension spindles shall be provided.
The variety and type of supports for ducts and fans shall be kept to a minimum and their
design shall be such as to facilitate quick and secure fixing to metal, concrete, brickwork
and wood.
Where the design of the structure is in reinforced concrete, supports shall be secured to the
structure by means of redheads, raw bolts or other approved means.
Where the subcontractor proposes to secure his supports by other means than to the main
structural concrete, he shall consult with the Engineer before proceeding.
3.0 DUCTWORK
The subcontractor shall supply, deliver and erect all ductwork as shown on the contract
drawings.
All ductwork shall be manufactured in accordance with the Heating and ventilation
contractors Association 9H.V.C.A.0 specification DW/142. 1982 except where stated
otherwise.
Ductwork shall be manufactured from galvanized mild steel sheet unless specified
otherwise. All external ductwork shall be manufactured from black mild steel sheet which
shall be galvanized after manufacture.
All seams shall be lock form type. All ductwork systems shall be complete with all
necessary dampers, bends, tees, tapers, transformation and special pieces.Where removal is required for access or maintenance, ducting shall be provided with steel
angle flanged joints suitably painted and protected against rust.
Only bends type 1-7 inclusive detailed in the H.V.C.A specification will be permitted.
Only duct connections type 42-44 inclusive, 53 and 54 as detailed in the H.V.C.A
specification will be permitted. All joints shall be fixed as to be suitable for the direction of
air flow.
All proposed positions for the plant and ductwork shall be confirmed on site prior to
development of shop drawings and manufacture of ducts.
Transformation and Taper pieces shall , wherever possible, be constructed so that the
included angle does not exceed 30 degrees.
All flanged joints shall be sealed by the use of asbestos string or equivalent material
compressed between the flanges , and where slip joints occur, these shall be sealed by
‘prestik’ or other similar jointing compound and adhesive tape 40mm wide.
Dampers shall be of aerofoil section and manufactured from galvanized mild steel sheet.
Damper plates shall not exceed 150 mm in width and the edges of the blades shall be sealed
with a 3 mm thick felt or rubber seal to minimize leakage.
Operating quadrants shall be provided with locknuts and the quadrants shall be clearly
marked with ‘open’ and closed’ positions.Multileaf damper blades shall be operated by one
arm through a linkage external to the duct.
The subcontractor shall provide sufficient access doors and handholds in the ductwork for
the purpose of maintenance and inspection. Access doors shall be of the hinged type anddoor openings shall be adequately stiffened and made airtight with purpose made rubber
gaskets around the door perimeter.
All supports and brackets shall be wire brushed and painted one coat of red oxide paint
prior to and after erection. Fastening of cables to ductwork shall not be permitted.
Where ductwork has insulation incorporating an external vapour seal, the ductwork shall be
insulated from the support by rot-proof softwood, hardwood or other suitable closed cell
insulator of not less than 25mm greater thickness than the insulation to be applied. This is
to ensure that the vapour seal may be bonded to the face of the timber, all as detailed in
clause 6.4 of the H.V.C.A specification DW/142. 1982.
Where ductwork passes through floors and walls, galvanized sheet sleeves or timber
frames ( builders work ) shall be provided. The space between duct and sleeve or frameshall be packed with asbestos rope or mastic to prevent air movement or noise transmission
from one controlled space to another. Ducts must not come into direct contact with the
building fabric.
Hangers and brackets shall be manufactured from rolled mild steel angle or channel
sections and shall generally be of the drop rod hanger or cantilever type. The hangers
shall be spaced to ensure adequate support. And where practicable shall be fitted at each
ductwork joint .
The subcontractor shall supply and install where called for , louvered inlets and outlets
with insect-proof screens. The louvers shall be constructed throughout from extruded
aluminum sections and shall have a lacquered or anodized finish to prevent corrosion. The
louvers shall be weather-proof and have a free area of not less than 50 %.The subcontractor shall ensure that wherever fans or similar equipment are connected to
the ductwork system , the connections are made with a heavy duty rod and vermin-proof
neoprene , or similar material, flexible connection to prevent vibration transmission to the
ductwork or building fabric. Flexible connections shall be secured by a pre-drilled mating
flange, or when fixing to a spigot , the spigot should be beaded and a jubilee clip or split
flat iron ring should be used.
5.0 TESTING AND INSPECTIONS
5.1 SITE TESTS:
The subcontractor shall provide all labour, materials, apparatus and properly calibratedand certified instruments and equipment necessary to carry out site tests and shall arrange
with other sub-contractors for the testing of associated equipment which may affect the
Performance of the plant installed under these subcontract works.
The tests on air flow and pumped water circulation systems shall be carried out in
accordance with the appropriate British standard specification and appropriate codes of
practice, the relevant CIBSE commissioning codes and regulations for the Electrical
Equipment of buildings issued by the institution of Electrical Engineers.
5.2 SITE TESTS – FANS:
All fans shall be charged with a suitable lubricant and shall be tested upon completion of
the ancillary system erection to ascertain that the performance of each fan complies with
the requirements of the specification.
5.3 COMPLETION OF WORKS AND TESTING:
Following the site test and prior to hand-over, mechanical ventilation or air-conditioningsystems shall be balanced by means of grilles, dampers and other special controls
installed, so as to give the required air flow rates and where applicable the desired
temperatures, pressures and humidity conditions in all areas served by the said systems.
The complete system shall be balanced and commissioned as a whole. Sectional balancing
and commissioning on any one part of the system where this excludes final complete
system balancing and commissioning, shall not be accepted.
Test volumes within ducts shall be within +/- 5% of the design volumes and volumes at the
grilles and diffusers shall be within +/- 10 % of the design volumes.
When the system has been balanced to the satisfaction of the Engineer, it shall be run under
automatic control for 72 hours continuous operation to ascertain any faults in operation
before acceptance and hand-over. Any faults discovered during this time shall be correctedand a further test or tests of 72 hours duration shall be carried out to ensure satisfactory
operation, all at the expense of the subcontractor.
5.4 COMPLETION OF WORKS - COMMISSIONING
For the purpose of this specification ‘commissioning shall mean the advancement of an
installation from the stage of static completion to full working order to specified
requirements. The object of commissioning procedures shall be to ensure that theinstallation operates in conformity with the requirements of the design specification.
Commissioning shall be carried out in accordance with the procedures as laid down in the
CIBSE commissioning codes : Series A- Air distribution, Series C- Automatic controls,
Series R- Refrigeration systems and series W- Water distribution systems. If the
subcontractor wishes to use alternative techniques these may be adopted subject to prior
discussion and agreement with the Engineer. The commissioning procedures shall include
demonstrations of the operation and function of all items of plant and their ability to
perform and maintain the full design requirements as described.
Specialist plant items such as water chillers and air handling units shall be started up and
set to work by the subcontractor according to the recommendations of the equipment
manufacturer or his approved representative. On composite or built up plant items such as
air handling plant , the contractor shall start up and set to work all constituent components.
Prior to running any item of electrical equipment, the subcontractor shall ensure that the
item of equipment has been correctly connected and that all fuses , overload etc. have been
set in accordance with the manufacturers recommendations . The subcontractor shall
ensure that the correct voltage is available on all supply phases, that the correct number of
phases are available to the equipment and that the power and control wiring to the
equipment has been connected in accordance with the manufacturer’s external wiring
diagrams.
It is essential that the results of checks and measurements are recorded in writing and no
commissioning procedure shall be deemed to be satisfactorily completed until the
regulation of the system has been demonstrated to the Engineer’s satisfaction. It is the
subcontractor’s responsibility to ensure that when a check or commissioning procedure has
been satisfactorily carried out , it is witnessed and the commissioning sheets are signed by
the Engineer.
On completion, the commissioning sheets shall be signed by the subcontractor and
countersigned by the Engineer. Acceptance of the commissioning sheets shall not imply
acceptance of the complete installation. All documentation proposed for hand-over shall
be submitted to the Engineer for checking and comment.
6.0 FINISH PAINTING :
Upon completion of the installation and after all tests have been carried out to the satisfaction of the
Engineer, the plant, equipment, supports etc, shall be examined and all priming coats damaged
during erection made good.
Any plant or equipment, ductwork etc, which is to be insulated, shall have had the priming
coat made good before application of the insulation.
After the above procedures have been carried out to the satisfaction of the Engineer, the
various surfaces shall be given the necessary preparation as recommended by the paint and
insulation manufacturers and finish painted in colors to be agreed between thesubcontractor and the Architect at a later date.
For the purpose of the specification, however, it shall be deemed that the subcontractor’s
tender price was based on the identification requirements for the various services detailed
in code of practice DW/161 Identification of ductwork as published by the H.V.C.A.
Adequate notice in writing shall be given to the Engineer by the subcontractor stating his
intention to carry out any of the commissioning procedures and this period shall not be less
than 7 working days. The subcontractor shall complete detailed ‘commissioning sheets’
and shall submit to the Engineer for review copies of the proposed schedules to be used for
the commissioning checks prior to the commencement of commissioning. The Engineer
shall not attend the site for the purpose of witnessing acceptance tests and commissioningdemonstrations until the commissioning sheets are submitted to the Engineer for his
The site of the proposed subcontract works is Mombasa Polytechnic University College
-Mombasa
3.1.2 Description of the Project:
The project involves the installation of a new mechanical ventilation system.
3.1.3 Commencement of Works:The subcontractor in submitting his tender shall be deemed to have included for
commencing any necessary work on site at such time as will comply with the main
contractor’s programme.
3.1.4 Climatic conditions:
The following climatic conditions apply at the site of the works and all plant, equipment,
materials and installations shall be suitable for these conditions.
Maximum temperature 32 °C
Minimum temperature 7 °C
Average temperature 13° C
Relative Humidity 48-95 %Altitude 5 m above sea level
Rainfall Can be extremely heavy at certain periods of the year.
The subcontractor shall be deemed to have taken into account all the above details in his
prices and planning for the execution of the works.
3.1.5 Internal Conditions:
Temperature 22+/- 2 ° C
Relative Humidity 30- 70 %
Noise level NC 35.
The cold rooms, freezer room and air-conditioning systems are designed to maintain the
following internal conditions with the ambient design conditions of 30 ° C DB.
3.2.0 SCOPE OF WORKS
The subcontract shall comprise the supply ,delivery, installation, setting to work, testing
and commissioning of all the materials and equipment called for in this specification or
shown on the drawings.
The subcontract shall include for all appurtenances(accessories) and appliances, notnecessarily called for in this specification or on the contract drawings but which are
necessary for the completion and satisfactory functioning of the works.
Discharge and fresh air intake louvers shall be similar or equal to type WG/EF as
manufactured by Waterloo CO. Ltd.
They shall be manufactured from robust Aluminum alloy extrusions with lacquered finish.
An insect screen shall be fixed to the back of the louvers. All louvers shall have a minimum
of 50 % free area.
3.6.3 INSULATION
Any external ductwork shall be wrapped with roofing felt properly lapped to ensure a
waterproof covering. All cooled air ducts shall be insulated with either expanded
polystyrene sheet or sprayed polyurethane foam without gaps using suitable adhesive and
plastic impingement pines attached to ductwork.
3.6.4 ROOM OR SPACE THERMOSTATS
These shall be located in the extract duct immediately after the air-conditioned space andwired to the air conditioner control system. The thermometer shall have a range of 15 ° C to
35 °C. The thermostat shall be set at the required room temperature and should maintain the
temperature with a differential of 1°C.
3.6.5 TEMPERATURE AND HUMIDITY CONTROL
The temperature and humidity control, overriding on humidity shall be affected from
detectors mounted on the return air duct. The resultant signal from the control unit shall
cause the motorized step controller on A-C unit to step up or down accordingly.
3.6.6 EXTRACT FANSThe extract fans shall be duct-mounted continuously rated axial flow fans as ‘woods’
Aerofoil axial flow fans double stage or equal and approved.
The case work of both the bowler unit (BPH) and condenser (RAC) shall be galvanized
steel with polyester paint finish. The evaporator coil in BPH shall be manufactured from
copper tube mechanically bounded or expanded into aluminum fins.
The compressor shall be of robust construction and high reliability. It shall be suitable for
use with refrigerant R22.
The condenser shall be of steel / copper tube with aluminum fins.
3.6.8 SUPPLY AIR DIFFUSERSShall be aluminum extruded four way rectangular or circular complete with dampers and
adjusters. They should be suitable for ceiling mounting. The sizes shall be as shown in the
bill of quantities.
3.6.9 RETURN AIR REGISTERS
Shall be aluminum with enamel finish: 4 way with opposed blade dampers.
3.7.0 DOOR TRANSFER GRILLES
Shall be similar to return air registers with paint to architect’s approval.
3.7.1 FLAP VALVES (NON RETURN AIR REGISTERS)
This shall be self closing dampers with minimum resistance to air flow under runningconditions and maximum resistance under reverse air flow conditions. Resilient strips or
other purpose made devices shall be provided to prevent rattling and for air sealing under
reverse flow.
3.7.2 BALANCING DAMPERS
The balancing dampers shall be provided and fixed at appropriate positions indicated on the
contract drawings. Damper blades shall be of rigid construction without sharp edges and
shall be substantially airtight. The dampers shall be multi-leaf type and be constructed indemountable ductwork sections, which shall extend beyond the swing of the blades.
Provisions shall be made for linkages to connect the multiple extended spindles. The
‘open’ and ‘closed’ positions shall be clearly marked on all dampers.
3.7.3 FLOW MEASURING POINTS
There shall be adequate flow measuring points in the ductwork to enable the proportional
balancing of the systems to be done. These shall be incorporated with volume control
dampers .
3.7.4 FIRE DAMPERS
Fire dampers shall be provided where indicated on the contract drawings. They shall besingle plate top hinged type . Each damper plate shall be held in the open position by a
fusible device set to release at a temperature of 72 °C.
3.7.5 FLEXIBLE CONNECTIONS
Flexible connections shall be provided where indicated on contract drawings.
The connections shall be made of tough tear-resistant and fire-resistant materials.